WO2023184329A1 - Feuille d'électrode positive, batterie secondaire et appareil électrique - Google Patents

Feuille d'électrode positive, batterie secondaire et appareil électrique Download PDF

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WO2023184329A1
WO2023184329A1 PCT/CN2022/084385 CN2022084385W WO2023184329A1 WO 2023184329 A1 WO2023184329 A1 WO 2023184329A1 CN 2022084385 W CN2022084385 W CN 2022084385W WO 2023184329 A1 WO2023184329 A1 WO 2023184329A1
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positive electrode
optionally
monomer unit
polymer
group
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PCT/CN2022/084385
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English (en)
Chinese (zh)
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刘会会
冯凌云
范艳煌
张文梦
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宁德时代新能源科技股份有限公司
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Priority to CN202280050821.9A priority Critical patent/CN117678092A/zh
Priority to EP22917641.7A priority patent/EP4280308A4/fr
Priority to PCT/CN2022/084385 priority patent/WO2023184329A1/fr
Priority to US18/222,503 priority patent/US20230420677A1/en
Publication of WO2023184329A1 publication Critical patent/WO2023184329A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of battery technology, and in particular to a positive electrode plate, a secondary battery and an electrical device.
  • secondary batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields.
  • energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, Military equipment, aerospace and other fields.
  • secondary batteries have achieved great development, higher requirements have been placed on their energy density, cycle performance, etc.
  • the related art uses a conductive undercoat layer between the active material of the positive electrode plate and the current collector to improve one or more properties of the secondary battery.
  • the new positive electrode sheet includes a new positive active material and a new conductive undercoat layer, which are described separately below.
  • a first aspect of the present application provides a positive electrode sheet, including a positive electrode current collector, a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and a conductive primer located between the positive electrode current collector and the positive electrode film layer. layer, where,
  • the positive electrode film layer includes a positive electrode active material with a core-shell structure, and the positive electrode active material includes a core and a shell covering the core,
  • the shell includes a first cladding layer covering the core and a second cladding layer covering the first cladding layer, wherein,
  • the first coating layer includes pyrophosphate MP 2 O 7 and phosphate XPO 4 , and the M and X are each independently selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr , one or more of Nb or Al;
  • the second cladding layer includes carbon
  • the conductive undercoat layer includes a first polymer, a first aqueous binder and a first conductive agent,
  • the first polymer includes:
  • At least one second monomer unit selected from the group consisting of the monomer unit represented by Formula 2 and the monomer unit represented by Formula 3;
  • At least one third monomer unit selected from the group consisting of the monomer unit represented by Formula 4 and the monomer unit represented by Formula 5;
  • R 1 , R 2 and R 3 each independently represent H, carboxyl group, ester group and the following substituted or unsubstituted groups: C1 to C10 alkyl group, C1 to C10 alkyl group Oxygen group, C2-C10 alkenyl group, C6-C10 aryl group, R 4 represents H, and the following substituted or unsubstituted groups: C1-C10 alkyl group, C1-C10 alkoxy group, C2-C10 Alkenyl group, C6 ⁇ C10 aryl group;
  • the mass percentage of the first monomer unit is M1, and M1 is 10% to 55%, optionally 25% to 55%; and/or,
  • the mass percentage of the second monomer unit is M2, and M2 is 40% to 80%, optionally 50% to 70%; and/or,
  • the mass percentage of the third monomer unit is M3, and M3 is 0% to 10%, optionally 0.001% to 2%; and/or,
  • the mass percentage of the fourth monomer unit is M4, and M4 is 0% to 10%, optionally 0.1% to 1%.
  • M3/(M2+M3) is 0% to 5%, optionally 0.001% to 1%.
  • the first polymer includes one or more selected from hydrogenated nitrile rubber and hydrogenated carboxyl nitrile rubber; and/or, the weight average molecular weight of the first polymer is 50,000 ⁇ 1.5 million, optionally 200,000 ⁇ 400,000.
  • the first water-based binder includes one selected from the group consisting of water-based polyacrylic resin and its derivatives, water-based amino-modified polypropylene resin and its derivatives, polyvinyl alcohol and its derivatives, or Multiple, optionally including selected from water-based acrylic acid-acrylate copolymer; and/or, the weight average molecular weight of the first water-based binder is 200,000 to 1.5 million, optionally 300,000 to 400,000.
  • the first conductive agent includes one selected from the group consisting of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, or Multiple types, optionally including one or more selected from carbon nanotubes, graphene, and carbon nanofibers.
  • the mass percentage of the first polymer is X1, and X1 is 5% to 20%, optionally 5% to 10%; and/or,
  • the mass percentage of the first water-based binder is X2, and X2 is 30% to 80%, optionally 40% to 50%; and/or,
  • the mass percentage of the first conductive agent is X3, and X3 is 10% to 50%, optionally 40% to 50%.
  • the thickness of the conductive undercoat layer ranges from 1 ⁇ m to 20 ⁇ m, optionally from 3 ⁇ m to 10 ⁇ m.
  • the positive electrode film layer further includes one or more selected from the group consisting of a wetting agent and a dispersing agent.
  • the positive electrode film layer also includes both a wetting agent and a dispersing agent.
  • the surface tension of the sizing agent is 20 mN/m to 40 mN/m.
  • the sizing agent includes one or more selected from the group consisting of small molecule organic solvents and low molecular weight polymers,
  • the small molecule organic solvent includes one or more selected from the group consisting of alcohol amine compounds, alcohol compounds, and nitrile compounds.
  • the number of carbon atoms of the alcohol amine compound is 1 to 16, optionally 2 to 6;
  • the low molecular weight polymer includes one or more selected from the group consisting of maleic anhydride-styrene copolymer, polyvinylpyrrolidone, and polysiloxane.
  • the low molecular weight polymer The weight average molecular weight is below 6000, optionally 3000-6000.
  • the dispersant includes a second polymer, and the second polymer includes:
  • At least one sixth monomer unit selected from the group consisting of a monomer unit represented by Formula 8 and a monomer unit represented by Formula 9;
  • At least one seventh monomer unit selected from the group consisting of the monomer unit represented by Formula 10 and the monomer unit represented by Formula 11;
  • the mass percentage of the fifth monomer unit is M5, and M5 is 10% to 55%, optionally 25% to 55%; and/or,
  • the mass percentage of the sixth monomer unit is M6, and M6 is 40% to 80%, optionally 50% to 70%; and/or,
  • the mass percentage of the seventh monomer unit is M7, and M7 is 0% to 10%, optionally 0.001% to 2%.
  • M7/(M6+M7) is 0% to 5%, optionally 0.001% to 1%.
  • the second polymer is hydrogenated nitrile rubber; and/or,
  • the weight average molecular weight of the second polymer is 50,000-500,000, optionally 150,000-350,000.
  • the mass percentage of the dispersant is Y1, and Y1 is 0.05% to 1%, optionally 0.1% to 0.5%; and/or, The mass percentage of the sizing agent is Y2, and Y2 is 0.05% to 2%, optionally 0.2% to 0.8%.
  • Y1/Y2 is 0.05-20, optionally 0.1-1, further 0.3-0.8.
  • the mass ratio of the first polymer to the second polymer is 1.5-5, optionally 2-3.
  • the interplanar spacing of the phosphate of the first coating layer is 0.345-0.358 nm, and the angle between the crystal directions (111) is 24.25°-26.45°;
  • the interplanar spacing of phosphate is 0.293-0.326nm, and the angle between the crystal orientation (111) is 26.41°-32.57°.
  • the ratio of y to 1-y is 1:10 to 10:1, optionally 1:4 to 1:1; and/or, in the kernel, z
  • the ratio to 1-z is 1:9 to 1:999, optionally 1:499 to 1:249.
  • the coating amount of the first coating layer is greater than 0% by weight and less than or equal to 7% by weight, optionally 4-5.6% by weight, based on the weight of the core.
  • the weight ratio of pyrophosphate and phosphate in the first coating layer is 1:3 to 3:1, optionally 1:3 to 1:1.
  • the crystallinity of the pyrophosphate and phosphate salts each independently ranges from 10% to 100%, optionally from 50% to 100%.
  • the coating amount of the second coating layer is greater than 0% by weight and less than or equal to 6% by weight, optionally 3-5% by weight, based on the weight of the core.
  • the A is selected from at least two of Fe, Ti, V, Ni, Co and Mg.
  • the Li/Mn anti-site defect concentration of the cathode active material is 4% or less, optionally 2% or less.
  • the lattice change rate of the cathode active material is 6% or less, optionally 4% or less.
  • the surface oxygen valence state of the cathode active material is -1.88 or less, optionally -1.98 to -1.88.
  • the positive active material has a compacted density of 2.0 g/cm or more at 3 tons, optionally 2.2 g/cm or more.
  • the specific surface area of the positive active material is 15 m 2 /g ⁇ 25 m 2 /g, and the coating weight of one side of the positive current collector is 20 mg/cm 2 ⁇ 40 mg/cm 2 .
  • the specific surface area of the cathode active material is 15m 2 /g ⁇ 25m 2 /g and the coating weight of one side of the cathode current collector is 20mg/cm 2 ⁇ 40mg/cm 2
  • the film release phenomenon is prone to occur during the coating process.
  • This application uses a new type of conductive undercoat to increase the bonding strength between the positive active material layer and the current collector.
  • a second aspect of the present application provides a secondary battery, including the positive electrode plate described in any one of the above.
  • a third aspect of the present application provides an electrical device, including the above-mentioned secondary battery.
  • the cathode active material with a core-shell structure includes a core and a shell covering the core,
  • the shell includes a first cladding layer covering the core and a second cladding layer covering the first cladding layer,
  • the first coating layer includes pyrophosphate MP 2 O 7 and phosphate XPO 4 , wherein M and X are each independently selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, One or more of Ag, Zr, Nb or Al;
  • the second cladding layer includes carbon.
  • the above limitation on the numerical range of y is not only a limitation on the stoichiometric number of each element as A, but also on the stoichiometric number of each element as A.
  • Limitation of the sum of stoichiometric numbers For example, when A is two or more elements A1, A2...An, the stoichiometric numbers y1, y2...yn of A1, A2...An each need to fall within the numerical range of y defined in this application, and y1 , y2...yn and the sum must also fall within this numerical range.
  • the limitation on the numerical range of the R stoichiometric number in this application also has the above meaning.
  • the inventor of the present application found in actual work that during the deep charge and discharge process of the lithium manganese phosphate cathode active material, manganese dissolution is relatively serious. Although there are attempts in the prior art to coat lithium manganese phosphate with lithium iron phosphate to reduce interface side reactions, this coating cannot prevent the migration of eluted manganese into the electrolyte. The eluted manganese is reduced to metallic manganese after migrating to the negative electrode. The metal manganese produced is equivalent to a "catalyst", which can catalyze the decomposition of the SEI film (solid electrolyte interphase, solid electrolyte interface film) on the surface of the negative electrode.
  • Part of the by-products produced are gases, which can easily cause the battery to expand and affect the safety of the secondary battery. Performance, and the other part is deposited on the surface of the negative electrode, blocking the passage of lithium ions in and out of the negative electrode, causing the impedance of the secondary battery to increase and affecting the dynamic performance of the battery. In addition, in order to replenish the lost SEI film, the electrolyte and active lithium inside the battery are continuously consumed, which has an irreversible impact on the capacity retention rate of the secondary battery.
  • the inventor found that for lithium manganese phosphate cathode active materials, problems such as severe manganese dissolution and high surface reactivity may be caused by the Ginger-Taylor effect of Mn 3+ after delithiation and the change in the size of the Li + channel.
  • the inventor modified lithium manganese phosphate to obtain a cathode active material that can significantly reduce manganese dissolution and lattice change rate, and thus has good cycle performance, high-temperature storage performance and safety performance.
  • the lithium manganese phosphate cathode active material of the present application has a core-shell structure with two coating layers.
  • the positive active material includes a core 91 and a shell covering the core.
  • the shell includes a first coating layer 92 that wraps the core and a second coating layer 93 that wraps the first coating layer 92 .
  • the core includes Li 1+x Mn 1-y A y P 1-z R z O 4 .
  • the element A doped in the manganese position of lithium manganese phosphate in the core helps to reduce the lattice change rate of lithium manganese phosphate during the lithium deintercalation process, improves the structural stability of the lithium manganese phosphate cathode material, and greatly reduces the dissolution of manganese. And reduce the oxygen activity on the particle surface.
  • the element R doped at the phosphorus site helps change the ease of Mn-O bond length change, thereby reducing the lithium ion migration barrier, promoting lithium ion migration, and improving the
  • the first coating layer of the cathode active material of the present application includes pyrophosphate and phosphate. Since the migration barrier of transition metals in pyrophosphate is high (>1eV), it can effectively inhibit the dissolution of transition metals. Phosphate has excellent ability to conduct lithium ions and can reduce the surface miscellaneous lithium content. In addition, since the second coating layer is a carbon-containing layer, it can effectively improve the conductive properties and desolvation ability of LiMnPO 4 . In addition, the "barrier" function of the second coating layer can further hinder the migration of manganese ions into the electrolyte and reduce the corrosion of the active material by the electrolyte.
  • this application can effectively suppress the dissolution of Mn during the process of deintercalation of lithium, and at the same time promote the migration of lithium ions, thereby improving the rate performance of the battery core and improving the secondary Battery cycle performance and high temperature performance.
  • Figure 10 is a comparison chart between the XRD spectrum of Example 1-1 of the present application before the first coating layer and the second coating layer are not coated, and the standard XRD spectrum of lithium manganese phosphate (00-033-0804). It should be pointed out that, as shown in Figure 10, in this application, by comparing the XRD spectra before and after LiMnPO 4 doping, it can be seen that the positions of the main characteristic peaks of the cathode active material of this application and LiMnPO 4 before doping are basically consistent, indicating that the doping
  • the mixed lithium manganese phosphate cathode active material has no impurity phase.
  • the improvement in secondary battery performance mainly comes from element doping, not the impurity phase.
  • the interplanar spacing of the phosphate of the first coating layer is 0.345-0.358 nm, and the angle between the crystal directions (111) is 24.25°-26.45°; the first coating layer The interplanar spacing of pyrophosphate is 0.293-0.326nm, and the angle between the crystal orientation (111) is 26.41°-32.57°.
  • the angle between the interplanar spacing and the crystal direction (111) of the phosphate and pyrophosphate in the first coating layer is within the above range, the impurity phase in the coating layer can be effectively avoided, thereby increasing the gram capacity of the material and improving cycle performance. performance and rate capabilities.
  • the ratio of y to 1-y is 1:10 to 10:1, optionally 1:4 to 1:1.
  • y represents the sum of stoichiometric numbers of Mn-site doping elements.
  • the ratio of z to 1-z is 1:9 to 1:999, optionally 1:499 to 1:249.
  • y represents the sum of stoichiometric numbers of P-site doping elements.
  • the coating amount of the first coating layer is greater than 0% by weight and less than or equal to 7% by weight, optionally 4-5.6% by weight, based on the weight of the core.
  • the coating amount of the first coating layer is within the above range, manganese dissolution can be further suppressed and the transport of lithium ions can be further promoted. And can effectively avoid the following situations: if the coating amount of the first coating layer is too small, the inhibitory effect of pyrophosphate on manganese dissolution may be insufficient, and the improvement of lithium ion transport performance is not significant; if If the coating amount of a coating layer is too large, the coating layer may be too thick, increase the battery impedance, and affect the dynamic performance of the battery.
  • the weight ratio of pyrophosphate and phosphate in the first coating layer is 1:3 to 3:1, optionally 1:3 to 1:1.
  • the appropriate ratio of pyrophosphate and phosphate is conducive to giving full play to the synergistic effect of the two. And can effectively avoid the following situations: if there is too much pyrophosphate and too little phosphate, it may cause the battery impedance to increase; if there is too much phosphate and too little pyrophosphate, the effect of inhibiting manganese dissolution is not significant.
  • the crystallinity of the pyrophosphate and phosphate salts each independently ranges from 10% to 100%, optionally from 50% to 100%.
  • pyrophosphate and phosphate with a certain degree of crystallinity are beneficial to maintaining the structural stability of the first coating layer and reducing lattice defects.
  • this is conducive to giving full play to the role of pyrophosphate in hindering manganese dissolution.
  • it is also conducive to the phosphate reducing the surface miscellaneous lithium content and reducing the valence state of surface oxygen, thereby reducing the interface side reactions between the cathode material and the electrolyte and reducing The consumption of electrolyte improves the cycle performance and safety performance of the battery.
  • the crystallinity of pyrophosphate and phosphate can be adjusted, for example, by adjusting the process conditions of the sintering process, such as sintering temperature, sintering time, and the like.
  • the crystallinity of pyrophosphate and phosphate can be measured by methods known in the art, such as by X-ray diffraction, density, infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance absorption methods.
  • the coating amount of the second coating layer is greater than 0% by weight and less than or equal to 6% by weight, optionally 3-5% by weight, based on the weight of the core.
  • the carbon-containing layer as the second coating layer can function as a "barrier” to avoid direct contact between the positive active material and the electrolyte, thereby reducing the corrosion of the active material by the electrolyte and improving the safety performance of the battery at high temperatures.
  • it has strong electrical conductivity, which can reduce the internal resistance of the battery, thereby improving the dynamic performance of the battery.
  • the carbon material has a low gram capacity, when the amount of the second coating layer is too large, the overall gram capacity of the cathode active material may be reduced. Therefore, when the coating amount of the second coating layer is within the above range, the kinetic performance and safety performance of the battery can be further improved without sacrificing the gram capacity of the cathode active material.
  • the A is selected from at least two of Fe, Ti, V, Ni, Co and Mg.
  • Doping the manganese site in the lithium manganese phosphate cathode active material with two or more of the above elements at the same time is beneficial to enhancing the doping effect. On the one hand, it further reduces the lattice change rate, thereby inhibiting the dissolution of manganese and reducing the loss of electrolyte and active lithium. consumption, on the other hand, it is also conducive to further reducing surface oxygen activity and reducing interface side reactions between the positive active material and the electrolyte, thereby improving the cycle performance and high-temperature storage performance of the battery.
  • the Li/Mn anti-site defect concentration of the cathode active material is 4% or less, optionally 2% or less.
  • the Li/Mn anti-site defect refers to the interchange of positions of Li + and Mn 2+ in the LiMnPO 4 crystal lattice. Since the Li + transport channel is a one-dimensional channel, Mn 2+ is difficult to migrate in the Li + transport channel. Therefore, the anti-site defective Mn 2+ will hinder the transport of Li + .
  • the anti-site defect concentration can be measured based on JIS K0131-1996, for example.
  • the lattice change rate of the cathode active material is 6% or less, optionally 4% or less.
  • the lithium deintercalation process of LiMnPO 4 is a two-phase reaction.
  • the interface stress of the two phases is determined by the lattice change rate. The smaller the lattice change rate, the smaller the interface stress and the easier Li + transport. Therefore, reducing the lattice change rate of the core will be beneficial to enhancing the Li + transport capability, thereby improving the rate performance of secondary batteries.
  • the average discharge voltage of the cathode active material is more than 3.5V, and the discharge capacity is more than 140mAh/g; optionally, the average discharge voltage is more than 3.6V, and the discharge capacity is more than 145mAh. /g or above.
  • the average discharge voltage of undoped LiMnPO 4 is above 4.0V, its discharge gram capacity is low, usually less than 120mAh/g. Therefore, the energy density is low; adjusting the lattice change rate by doping can make it The discharge gram capacity is greatly increased, and the overall energy density is significantly increased while the average discharge voltage drops slightly.
  • the surface oxygen valence state of the cathode active material is -1.88 or less, optionally -1.98 ⁇ -1.88.
  • the higher the valence state of oxygen in the compound the stronger its ability to obtain electrons, that is, the stronger its oxidizing property.
  • the reactivity on the surface of the cathode material can be reduced, and the interface side reactions between the cathode material and the electrolyte can be reduced, thereby improving the secondary Battery cycle performance and high temperature storage performance.
  • the compacted density of the positive active material at 3 tons (T) is above 2.0 g/cm 3 , optionally above 2.2 g/cm 3 .
  • the compacted density of the positive active material that is, the greater the weight of the active material per unit volume, the more conducive it will be to increasing the volumetric energy density of the battery.
  • the compacted density can be measured according to GB/T 24533-2009, for example.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes the lithium manganese phosphate positive electrode active material of the present application or is prepared according to the method of the present application. lithium manganese phosphate cathode active material, and the content of the cathode active material in the cathode film layer is more than 10% by weight, based on the total weight of the cathode film layer.
  • the content of the cathode active material in the cathode film layer is 90-99.5% by weight, based on the total weight of the cathode film layer.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the cathode film layer of the present application includes 90-99.5% of the lithium manganese phosphate cathode active material of the present application, 0.4-5.5% of binder, 0.1-2.5% of conductive carbon and 0.001-1% of Other additives, based on the total weight of the positive electrode film layer.
  • the positive electrode film layer of the present application may also include other additives such as dispersants, wetting agents, rheology modifiers and other additives commonly used in the art.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the coating weight of the positive electrode film layer of the present application is 0.28-0.45g/1540.25mm 2 , and the compacted density reaches 2.2-2.8g/cm 3 .
  • the median particle diameter Dv 50 refers to the particle diameter corresponding to when the cumulative volume distribution percentage of the positive active material reaches 50%.
  • the median particle diameter Dv 50 of the positive electrode active material can be measured using laser diffraction particle size analysis. For example, refer to the standard GB/T 19077-2016 and use a laser particle size analyzer (such as Malvern Master Size 3000) for measurement.
  • coating layer refers to a material layer coated on the core.
  • the material layer may completely or partially cover the core.
  • the use of “coating layer” is only for convenience of description and is not intended to limit this article. invention.
  • the term “thickness of the coating layer” refers to the thickness of the material layer coating the core in the radial direction of the core.
  • source refers to a compound that is the source of a certain element.
  • types of “source” include but are not limited to carbonates, sulfates, nitrates, elements, halides, and oxides. and hydroxides, etc.
  • This application modified lithium manganese phosphate to obtain a cathode active material that can significantly reduce manganese dissolution and lattice change rate, and thus has good cycle performance, high-temperature storage performance and safety performance.
  • the first coating layer of the cathode active material of the present application includes pyrophosphate and phosphate. Since the migration barrier of transition metals in pyrophosphate is high (>1eV), it can effectively inhibit the dissolution of transition metals. Phosphate has excellent ability to conduct lithium ions and can reduce the surface miscellaneous lithium content. In addition, since the second coating layer is a carbon-containing layer, it can effectively improve the conductive properties and desolvation ability of LiMnPO 4 .
  • the "barrier" function of the second coating layer can further hinder the migration of manganese ions into the electrolyte and reduce the corrosion of the active material by the electrolyte. Therefore, by performing specific element doping and surface coating on lithium manganese phosphate, this application can effectively suppress the dissolution of Mn during the process of deintercalation of lithium, and at the same time promote the migration of lithium ions, thereby improving the rate performance of the battery core and improving the secondary Battery cycle performance and high temperature performance.
  • the first polymer in the conductive undercoat layer will dissolve again after contacting the solvent NMP. , thereby mutually diffusing with the positive electrode active material slurry. After solidification, the active material layer can be integrated with the base coating, thereby effectively increasing the bonding strength between the positive electrode film layer and the positive electrode current collector.
  • the first water-based binder in the conductive undercoat layer is acrylic-acrylate copolymer (weight average molecular weight: 200000 ⁇ 1500000), the polarity of the binder is strong and can be combined with the current collector (aluminum foil ) good adhesion.
  • acrylic acid-acrylate copolymer has good stability in electrolyte, high temperature resistance, corrosion resistance, and low electrolyte absorption efficiency (low swelling degree).
  • the conductive agent in the conductive undercoat layer is selected from one or two types of carbon black, acetylene black, carbon fiber, graphite, and carbon nanotubes, it can reduce the interface resistance and improve the charge and discharge rate performance of the battery. and extend battery cycle life.
  • Figure 1 is a schematic diagram of a positive electrode plate according to an embodiment of the present application.
  • Figure 2 is a schematic flow chart of measuring the adhesive force of pole pieces according to an embodiment of the present application
  • FIG. 3 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 4 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 7 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 6 .
  • FIG. 8 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Figure 9 is a schematic diagram of a cathode active material with a core-shell structure according to an embodiment of the present application.
  • Figure 10 is a comparison chart between the XRD spectrum of Example 1-1 of the present application before the first coating layer and the second coating layer are not coated, and the standard XRD spectrum of lithium manganese phosphate (00-033-0804).
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • Secondary batteries also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • a secondary battery normally includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte.
  • active ions such as lithium ions
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows active ions to pass through.
  • the electrolyte is between the positive electrode piece and the negative electrode piece and mainly plays the role of conducting active ions.
  • a first aspect of the present application provides a positive electrode sheet, including a positive electrode current collector, a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and a conductive primer located between the positive electrode current collector and the positive electrode film layer. layer, where,
  • the positive electrode film layer includes a positive electrode active material with a core-shell structure, and the positive electrode active material includes a core and a shell covering the core,
  • the shell includes a first cladding layer covering the core and a second cladding layer covering the first cladding layer, wherein,
  • the first coating layer includes pyrophosphate MP 2 O 7 and phosphate XPO 4 , and the M and X are each independently selected from Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr , one or more of Nb or Al;
  • the second cladding layer includes carbon
  • the conductive undercoat layer includes a first polymer, a first aqueous binder and a first conductive agent,
  • the first polymer includes:
  • At least one second monomer unit selected from the group consisting of the monomer unit represented by Formula 2 and the monomer unit represented by Formula 3;
  • At least one third monomer unit selected from the group consisting of the monomer unit represented by Formula 4 and the monomer unit represented by Formula 5;
  • R 1 , R 2 and R 3 each independently represent H, carboxyl group, ester group and the following substituted or unsubstituted groups: C1 to C10 alkyl group, C1 to C10 alkyl group Oxygen group, C2-C10 alkenyl group, C6-C10 aryl group, R 4 represents H, and the following substituted or unsubstituted groups: C1-C10 alkyl group, C1-C10 alkoxy group, C2-C10 Alkenyl group, C6 ⁇ C10 aryl group;
  • the positive electrode film layer and the positive electrode current collector have enhanced bonding strength.
  • the cathode active material slurry containing solvent N-methylpyrrolidone, NMP for short
  • the first polymer in the conductive undercoat layer will Dissolved again, thereby mutually diffusing with the positive electrode active material slurry.
  • the active material layer can be integrated with the base coating, thereby effectively increasing the bonding strength between the positive electrode film layer and the positive electrode current collector.
  • the first polymer is a random copolymer.
  • Nitrile butadiene rubber is a random copolymer formed by polymerization (such as emulsion polymerization) of acrylonitrile and butadiene monomers. Its general structural formula is:
  • connection mode of butadiene (B) and acrylonitrile (A) chain links is generally the triplet of BAB, BBA or ABB, ABA and BBB.
  • BAB butadiene
  • ABB acrylonitrile
  • AABAA acrylonitrile
  • sequence distribution of butadiene is mainly trans-1,4 structure, and its microstructure is related to the polymerization conditions.
  • Hydrogenated nitrile butadiene rubber refers to a product obtained by hydrogenating the carbon-carbon double bonds on the molecular chain of nitrile butadiene rubber until it is partially or fully saturated.
  • the chemical formula of fully saturated hydrogenated nitrile rubber is as follows:
  • HNBR hydrogenated nitrile rubber
  • the so-called hydrogenated carboxybutyl rubber refers to the further introduction of carboxyl groups on the basis of hydrogenated nitrile rubber.
  • Esters of unsaturated carboxylic acids are, for example, esters of ⁇ , ⁇ -unsaturated monocarboxylic acids.
  • Useful esters of ⁇ , ⁇ -unsaturated monocarboxylic acids are their alkyl esters and alkoxyalkyl esters.
  • an alkyl ester of ⁇ , ⁇ -unsaturated monocarboxylic acid such as C1-C18 alkyl ester
  • optionally is an alkyl ester of acrylic acid or methacrylic acid such as C1-C18 alkyl ester
  • alkoxyalkyl esters of ⁇ , ⁇ -unsaturated monocarboxylic acids optionally alkoxyalkyl esters of acrylic acid or methacrylic acid, for example C2-C12-alkanes of acrylic acid or methacrylic acid.
  • Oxyalkyl esters particularly methoxymethyl acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and methoxyethyl (meth)acrylate.
  • Mixtures of alkyl esters, such as those described above, and alkoxyalkyl esters, such as those described above, may also be used.
  • Hydroxyalkyl acrylate and hydroxyalkyl methacrylate in which the number of carbon atoms in the hydroxyalkyl group is 1-12 can also be used, optionally 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and acrylic acid. 3-hydroxypropyl ester.
  • epoxy-containing esters may be used, such as glycidyl methacrylate.
  • Cyanoalkyl acrylate and cyanoalkyl methacrylate with 2-12 C atoms in the cyanoalkyl group can also be used, and ⁇ -cyanoethyl acrylate and ⁇ -cyanoethyl acrylate are optional. and cyanobutyl methacrylate.
  • Acrylates or methacrylates containing fluorine-substituted benzyl groups can also be used, and fluorobenzyl acrylate and fluorobenzyl methacrylate are optional.
  • Fluoroalkyl-containing acrylates and methacrylates can also be used, with optional trifluoroethyl acrylate and tetrafluoropropyl methacrylate.
  • Amino-containing ⁇ , ⁇ -unsaturated carboxylic acid esters such as dimethylaminomethyl acrylate and diethylaminoethyl acrylate may also be used.
  • the mass percentage of the first monomer unit is M1, and M1 is 10% to 55%, optionally 25% to 55%; and/or,
  • the mass percentage of the second monomer unit is M2, and M2 is 40% to 80%, optionally 50% to 70%; and/or,
  • the mass percentage of the third monomer unit is M3, and M3 is 0% to 10%, optionally 0.001% to 2%; and/or,
  • the mass percentage of the fourth monomer unit is M4, and M4 is 0% to 10%, optionally 0.1% to 1%.
  • the conductive undercoat based on this solution can be moderately dissolved during the coating process, thereby forming an enhanced bond with the positive electrode film layer.
  • the mass percentage of the first monomer unit is M1, and M1 is 10% to 55%, optionally 10%-15%, 15%-20%, 20%-25%, 25%-30% , 30%-35%, 35%-40%, 40%-45%, 45%-50% or 50%-55%; and/or,
  • the mass percentage of the second monomer unit is M2, and M2 is 40% to 80%, optionally 40%-45%, 45%-50%, 50%-55%, 55%-60% , 60%-65%, 65%-70%, 70%-75% or 75%-80%; and/or,
  • the mass percentage of the third monomer unit is M3, and M3 is 0% to 10%, optionally 0.001%-1%, 1%-2%, 2%-3%, 3%-4% , 4%-5%, 5%-6%, 6%-7%, 7%-8%, 8%-9% or 9%-10%; and/or,
  • the mass percentage of the fourth monomer unit is M4, and M4 is 0% to 10%, optionally 0.01%-1%, 1%-2%, 2%-3%, 3%-4% , 4%-5%, 5%-6%, 6%-7%, 7%-8%, 8%-9% or 9%-10%;.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the conductive undercoat based on this solution can be moderately dissolved during the coating process, thereby forming an enhanced bond with the positive electrode film layer.
  • M3/(M2+M3) is 0% to 5%, optionally 0.001% to 1%.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • M3/(M2+M3) is 0.01%-1%, 1%-2%, 2%-3%, 3%-4%, or 4%-5%.
  • the first polymer includes one or more selected from hydrogenated nitrile rubber and hydrogenated carboxyl nitrile rubber; and/or, the weight average molecular weight of the first polymer is 50,000 ⁇ 1.5 million, optionally 200,000 ⁇ 400,000.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the weight average molecular weight of the first polymer is 100,000-300,000, 300,000-500,000, 500,000-700,000, 700,000-900,000, 900,000-1.1 million, 1.10-1.3 million, or 130-150 Ten thousand.
  • the first water-based binder includes one selected from the group consisting of water-based polyacrylic resin and its derivatives, water-based amino-modified polypropylene resin and its derivatives, polyvinyl alcohol and its derivatives, or A variety, optionally including selected from waterborne acrylic-acrylate copolymers; and/or,
  • the weight average molecular weight of the first aqueous binder is 200,000 to 1.5 million, optionally 300,000 to 400,000.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the weight average molecular weight of the first aqueous binder is 100,000-300,000, 300,000-500,000, 500,000-700,000, 700,000-900,000, 900,000-1.1 million, or 1.10-1.3 million.
  • the first conductive agent includes one selected from the group consisting of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, or Multiple types, optionally including one or more selected from carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the mass percentage of the first polymer is X1, and X1 is 5% to 20%, optionally 5% to 10%; and/or,
  • the mass percentage of the first water-based binder is X2, and X2 is 30% to 80%, optionally 40% to 50%; and/or,
  • the mass percentage of the first conductive agent is X3, and X3 is 10% to 50%, optionally 40% to 50%.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the thickness of the conductive undercoat layer ranges from 1 ⁇ m to 20 ⁇ m, optionally from 3 ⁇ m to 10 ⁇ m.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the positive electrode film layer further includes one or more selected from the group consisting of a wetting agent and a dispersing agent.
  • the positive electrode film layer also includes both a wetting agent and a dispersing agent.
  • the surface tension of the sizing agent is 20 mN/m to 40 mN/m.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • surface tension can be measured using the Wilhelmy Plate Method.
  • Specific test steps can refer to general standards in the field, such as GBT/22237-2008 Determination of surfactant-surface tension, such as ASTM D1331-14.
  • the sizing agent includes one or more selected from the group consisting of small molecule organic solvents and low molecular weight polymers,
  • the small molecule organic solvent includes one or more selected from the group consisting of alcohol amine compounds, alcohol compounds, and nitrile compounds.
  • the number of carbon atoms of the alcohol amine compound is 1 to 16, optionally 2 to 6;
  • the low molecular weight polymer includes one or more selected from the group consisting of maleic anhydride-styrene copolymer, polyvinylpyrrolidone, and polysiloxane.
  • the low molecular weight polymer The weight average molecular weight is below 6000, optionally 3000-6000.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the dispersant includes a second polymer, and the second polymer includes:
  • At least one sixth monomer unit selected from the group consisting of the monomer unit represented by Formula 8 and the monomer unit represented by Formula 9;
  • At least one seventh monomer unit selected from the group consisting of the monomer unit represented by Formula 10 and the monomer unit represented by Formula 11;
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the mass percentage of the fifth monomer unit is M5, and M5 is 10% to 55%, optionally 25% to 55%; and/or,
  • the mass percentage of the sixth monomer unit is M6, and M6 is 40% to 80%, optionally 50% to 70%; and/or,
  • the mass percentage of the seventh monomer unit is M7, and M7 is 0% to 10%, optionally 0.001% to 2%.
  • the mass percentage of the fifth monomer unit is M5, and M5 is 10% to 55%, optionally 10%-15%, 15%-20%, 20%-25%, 25%-30% , 30%-35%, 35%-40%, 40%-45%, 45%-50% or 50%-55%; and/or,
  • the mass percentage of the sixth monomer unit is M6, and M6 is 40% to 80%, optionally 40%-45%, 45%-50%, 50%-55%, 55%-60% , 60%-65%, 65%-70%, 70%-75% or 75%-80%; and/or,
  • the mass percentage of the seventh monomer unit is M7, and M7 is 0% to 10%, optionally 0.01%-1%, 1%-2%, 2%-3%, 3%-4% , 4%-5%, 5%-6%, 6%-7%, 7%-8%, 8%-9% or 9%-10%.
  • M7/(M6+M7) is 0% to 5%, optionally 0.001% to 1%.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the second polymer is hydrogenated nitrile rubber; and/or,
  • the weight average molecular weight of the second polymer is 50,000-500,000, optionally 150,000-350,000.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the mass percentage of the dispersant is Y1, and Y1 is 0.05% to 1%, optionally 0.1% to 0.5%; and/or, The mass percentage of the sizing agent is Y2, and Y2 is 0.05% to 2%, optionally 0.2% to 0.8%.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • Y1/Y2 is 0.05-20, optionally 0.1-1, further 0.3-0.8.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the mass ratio of the first polymer to the second polymer is 1.5-5, optionally 2-3.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the interplanar spacing of the phosphate of the first coating layer is 0.345-0.358 nm, and the angle between the crystal directions (111) is 24.25°-26.45°;
  • the interplanar spacing of phosphate is 0.293-0.326nm, and the angle between the crystal orientation (111) is 26.41°-32.57°.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the ratio of y to 1-y is 1:10 to 10:1, optionally 1:4 to 1:1; and/or, in the kernel, z
  • the ratio to 1-z is 1:9 to 1:999, optionally 1:499 to 1:249.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the coating amount of the first coating layer is greater than 0% by weight and less than or equal to 7% by weight, optionally 4-5.6% by weight, based on the weight of the core.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the weight ratio of pyrophosphate and phosphate in the first coating layer is 1:3 to 3:1, optionally 1:3 to 1:1.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the crystallinity of the pyrophosphate and phosphate salts each independently ranges from 10% to 100%, optionally from 50% to 100%.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the coating amount of the second coating layer is greater than 0% by weight and less than or equal to 6% by weight, optionally 3-5% by weight, based on the weight of the core.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the A is selected from at least two of Fe, Ti, V, Ni, Co and Mg.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the Li/Mn anti-site defect concentration of the cathode active material is 4% or less, optionally 2% or less.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the lattice change rate of the cathode active material is 6% or less, optionally 4% or less.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the surface oxygen valence state of the cathode active material is -1.88 or less, optionally -1.98 to -1.88.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the positive active material has a compacted density of 2.0 g/cm or more at 3 tons, optionally 2.2 g/cm or more.
  • the positive electrode sheet based on this solution is used in secondary batteries, and one or more properties of the secondary battery are significantly improved.
  • the present application provides a secondary battery including the positive electrode sheet described in any one of the above.
  • the present application provides an electrical device, including the above-mentioned secondary battery.
  • the positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes a positive electrode active material.
  • Figure 1 shows a schematic diagram of a positive electrode plate according to an embodiment.
  • a positive electrode sheet includes a positive electrode current collector 11, a positive electrode film layer 13 provided on at least one surface 112 of the positive electrode current collector 11, and a positive electrode film layer 13 located between the positive electrode current collector 11 and the positive electrode film layer 13.
  • Conductive primer layer 12 between.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer. At least one of a meta-copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and a fluorine-containing acrylate resin.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes a binder.
  • the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), At least one of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally also includes other auxiliaries, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • auxiliaries such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is liquid and includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally also includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 3 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 5 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • Figure 8 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the reaction kettle was heated to 80°C and stirred at a rotation speed of 600 rpm for 6 hours until the reaction was terminated (no bubbles were generated) to obtain a manganese oxalate suspension co-doped with Fe, Co, V and S.
  • the suspension was then filtered, and the filter cake was dried at 120° C. and then ground to obtain Fe, Co and V co-doped manganese oxalate dihydrate particles with a median particle size Dv50 of 100 nm.
  • Preparation of lithium manganese phosphate co-doped with Fe, Co, V and S combine the manganese oxalate dihydrate particles obtained in the previous step (1793.4g), 369.0g lithium carbonate (calculated as Li 2 CO 3 , the same below), 1.6g Dilute sulfuric acid with a concentration of 60% (calculated as 60% H 2 SO 4 , the same below) and 1148.9g ammonium dihydrogen phosphate (calculated as NH 4 H 2 PO 4 , the same below) were added to 20 liters of deionized water, and the mixture was Stir for 10 hours to mix evenly and obtain a slurry.
  • lithium iron pyrophosphate powder Dissolve 4.77g lithium carbonate, 7.47g ferrous carbonate, 14.84g ammonium dihydrogen phosphate and 1.3g oxalic acid dihydrate in 50ml deionized water. The pH of the mixture was 5, and the reaction mixture was stirred for 2 hours to fully react. The reacted solution was then heated to 80°C and maintained at this temperature for 4 hours to obtain a suspension containing Li 2 FeP 2 O 7. The suspension was filtered, washed with deionized water, and dried at 120°C for 4 hours. , get powder. The powder was sintered at 650° C. in a nitrogen atmosphere for 8 hours, and then naturally cooled to room temperature and then ground to obtain Li 2 FeP 2 O 7 powder.
  • lithium iron phosphate suspension Dissolve 11.1g lithium carbonate, 34.8g ferrous carbonate, 34.5g ammonium dihydrogen phosphate, 1.3g oxalic acid dihydrate and 74.6g sucrose (calculated as C 12 H 22 O 11 , the same below) In 150 ml of deionized water, a mixture was obtained, and then stirred for 6 hours to allow the above mixture to fully react. The reacted solution was then heated to 120°C and maintained at this temperature for 6 hours to obtain a suspension containing LiFePO4 .
  • the double-layer coated lithium manganese phosphate cathode active material prepared above, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) in a weight ratio of 92:2.5:5.5 ), stir and mix evenly to obtain positive electrode slurry. Then, the positive electrode slurry is evenly coated on the aluminum foil at a density of 0.280g/ 1540.25mm2 , dried, cold pressed, and cut to obtain the positive electrode piece.
  • negative active material artificial graphite artificial graphite, hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethylcellulose (CMC-Na) in a weight ratio of 90:5:2:2 : 1 Dissolve in solvent deionized water, stir and mix evenly to prepare negative electrode slurry.
  • the negative electrode slurry is evenly coated on the negative electrode current collector copper foil at a density of 0.117g/1540.25mm 2 , and then dried, cold pressed, and cut to obtain negative electrode pieces.
  • a commercially available PP-PE copolymer microporous film with a thickness of 20 ⁇ m and an average pore diameter of 80 nm was used.
  • the positive electrode piece, isolation film, and negative electrode piece obtained above are stacked in order, so that the isolation film is between the positive and negative electrodes to play an isolation role, and the bare battery core is obtained by winding.
  • the bare battery core is placed in the outer packaging, the above-mentioned electrolyte is injected and packaged to obtain a full battery (hereinafter also referred to as "full battery").
  • the double-layer coated lithium manganese phosphate cathode active material prepared above, PVDF, and acetylene black were added to NMP in a weight ratio of 90:5:5, and stirred in a drying room to form a slurry.
  • the above slurry is coated on aluminum foil, dried and cold pressed to form a positive electrode sheet.
  • the coating amount is 0.02g/cm 2 and the compacted density is 2.0g/cm 3 .
  • Lithium sheets were used as the negative electrode, and a solution of 1 mol/L LiPF 6 in ethylene carbonate (EC) + diethyl carbonate (DEC) + dimethyl carbonate (DMC) with a volume ratio of 1:1:1 was used as the electrolyte.
  • liquid, together with the positive electrode sheet prepared above, are assembled into a button battery (hereinafter also referred to as a "button battery") in a buckle box.
  • the coating amount shown in Table 1 is the same as that in Example 1.
  • the ratio of the coating amount corresponding to -1 is adjusted accordingly, so that the amounts of Li 2 FeP 2 O 7 /LiFePO 4 in Examples 1-2 to 1-6 are 12.6g/37.7g, 15.7g/47.1g, and 18.8 respectively. g/56.5g, 22.0/66.0g and 25.1g/75.4g.
  • the other conditions are the same as in Example 1-1 except that the amount of sucrose used is 37.3g.
  • the amounts of various raw materials are adjusted accordingly according to the coating amounts shown in Table 1 so that the amounts of Li 2 FeP 2 O 7 /LiFePO 4 are 23.6g/39.3g respectively. , 31.4g/31.4g, 39.3g/23.6g and 47.2g/15.7g, the conditions of Examples 1-11 to 1-14 were the same as Example 1-7.
  • Examples 1-15 were the same as Examples 1-14 except that 492.80 g of ZnCO3 was used instead of ferrous carbonate in the preparation process of the co-doped lithium manganese phosphate core.
  • Examples 1-16 used 466.4g NiCO 3 , 5.0g zinc carbonate and 7.2g titanium sulfate instead of ferrous carbonate in the preparation process of the co-doped lithium manganese phosphate core.
  • 455.2g of ferrous carbonate and 8.5g of vanadium dichloride were used in the preparation process of the lithium manganese phosphate core.
  • 455.2g of ferrous carbonate was used in the preparation process of the co-doped lithium manganese phosphate core.
  • 4.9g of vanadium dichloride and 2.5g of magnesium carbonate the conditions of Examples 1-17 to 1-19 were the same as Example 1-7.
  • Examples 1-19 used 369.4g of lithium carbonate and 1.05g of 60% concentrated dilute nitric acid instead of dilute sulfuric acid in the preparation process of the co-doped lithium manganese phosphate core.
  • the conditions of Examples 1-19 to 1-20 were the same as those of Example 1-18, except that 369.7g of lithium carbonate was used and 0.78g of silicic acid was used instead of dilute sulfuric acid.
  • Example 1-21 632.0g manganese carbonate, 463.30g ferrous carbonate, 30.5g vanadium dichloride, 21.0g magnesium carbonate and 0.78g silicic acid were used in the preparation process of the co-doped lithium manganese phosphate core. ;
  • Example 1-22 uses 746.9g manganese carbonate, 289.6g ferrous carbonate, 60.9g vanadium dichloride, 42.1g magnesium carbonate and 0.78g silicic acid in the preparation process of co-doped lithium manganese phosphate core. Except for this, the conditions of Examples 1-21 to 1-22 were the same as those of Example 1-20.
  • Example 1-24 In the preparation process of co-doped lithium manganese phosphate core, 862.1g manganese carbonate, 173.8g ferrous carbonate, 1155.1g ammonium dihydrogen phosphate, 1.86g boric acid (mass fraction 99.5% ) and 371.6 g of lithium carbonate, the conditions of Examples 1-23 to 1-24 were the same as those of Example 1-22.
  • Example 1-25 uses 370.1g lithium carbonate, 1.56g silicic acid and 1147.7g ammonium dihydrogen phosphate in the preparation process of the co-doped lithium manganese phosphate core, the conditions of Examples 1-25 are the same as those of Examples 1-20 are the same.
  • Examples 1-26, 368.3g lithium carbonate, 4.9g dilute sulfuric acid with a mass fraction of 60%, 919.6g manganese carbonate, 224.8g ferrous carbonate, and 3.7g dichloride were used in the preparation process of the co-doped lithium manganese phosphate core.
  • the conditions of Examples 1-26 were the same as Examples 1-20 except for vanadium, 2.5g magnesium carbonate and 1146.8g ammonium dihydrogen phosphate.
  • Example 1-27 used 367.9g lithium carbonate, 6.5g dilute sulfuric acid with a concentration of 60% and 1145.4g ammonium dihydrogen phosphate in the preparation process of the co-doped lithium manganese phosphate core.
  • the conditions of Example 1-27 Same as Examples 1-20.
  • Examples 1-28 to 1-33 are the same as those of Example 1-20, except that the usage amounts of dilute sulfuric acid with a concentration of 60% are: 8.2g, 9.8g, 11.4g, 13.1g, 14.7g and 16.3g respectively. .
  • the sintering temperature in the powder sintering step is 550°C and the sintering time is 1h to control the crystallinity of Li 2 FeP 2 O 7 to 30%.
  • the sintering temperature in the coating sintering step is 650°C and the sintering time is 2 hours to control the crystallinity of LiFePO 4 to 30%.
  • Other conditions are the same as in Example 1-1.
  • the sintering temperature in the powder sintering step is 550°C and the sintering time is 2h to control the crystallinity of Li 2 FeP 2 O 7 to 50%.
  • the sintering temperature in the coating sintering step is 650°C and the sintering time is 3 hours to control the crystallinity of LiFePO 4 to 50%.
  • Other conditions are the same as in Example 1-1.
  • the sintering temperature in the powder sintering step is 600°C and the sintering time is 3h to control the crystallinity of Li 2 FeP 2 O 7 to 70%.
  • the sintering temperature in the coating sintering step is 650°C and the sintering time is 4 hours to control the crystallinity of LiFePO 4 to 70%.
  • Other conditions are the same as in Example 1-1.
  • the sintering temperature in the powder sintering step is 650°C and the sintering time is 4h to control the crystallinity of Li 2 FeP 2 O 7 to 100%.
  • the sintering temperature in the coating sintering step is 700°C and the sintering time is 6 hours to control the crystallinity of LiFePO 4 to 100%.
  • Other conditions are the same as in Example 1-1.
  • the heating temperature/stirring time in the reaction kettle of Example 3-1 is 60°C/120 minutes respectively; the heating temperature in the reaction kettle of Example 3-2 The temperature/stirring time is 70°C/120 minutes respectively; the heating temperature/stirring time in the reaction kettle of Example 3-3 is 80°C/120 minutes respectively; the heating temperature/stirring time in the reaction kettle of Example 3-4 is respectively 90°C/120 minutes; the heating temperature/stirring time in the reaction kettle of Example 3-5 is 100°C/120 minutes respectively; the heating temperature/stirring time in the reaction kettle of Example 3-6 is 110°C/120 minutes respectively; The heating temperature/stirring time in the reaction kettle of Example 3-7 is 120°C/120 minutes respectively; the heating temperature/stirring time in the reaction kettle of Example 3-8 is 130°C/120 minutes respectively; the reaction of Example 3-9 The heating temperature/stirring time in the kettle is 100°C/60 minutes respectively;
  • Examples 4-1 to 4-4 Except in the preparation process of lithium iron pyrophosphate (Li 2 FeP 2 O 7 ), the drying temperature/drying time in the drying step are respectively 100°C/4h, 150°C/6h, 200°C/6h and 200°C/6h; in the preparation process of lithium iron pyrophosphate (Li 2 FeP 2 O 7 ), the sintering temperature and sintering time in the sintering step are 700°C/6h, 700°C/6h, 700 respectively Except for °C/6h and 600°C/6h, other conditions are the same as Example 1-7.
  • Embodiments 4-5 to 4-7 In addition to the drying temperature/drying time in the drying step during the coating process being 150°C/6h, 150°C/6h and 150°C/6h respectively; in the sintering process during the coating process The other conditions are the same as Examples 1-12 except that the sintering temperature and sintering time in the step are 600°C/4h, 600°C/6h and 800°C/8h respectively.
  • Preparation of manganese oxalate Add 1149.3g of manganese carbonate to the reaction kettle, and add 5 liters of deionized water and 1260.6g of oxalic acid dihydrate (calculated as C 2 H 2 O 4 ⁇ 2H 2 O, the same below). Heat the reaction kettle to 80°C and stir at 600 rpm for 6 hours until the reaction is terminated (no bubbles are generated) to obtain a manganese oxalate suspension, then filter the suspension, dry the filter cake at 120°C, and then proceed After grinding, manganese oxalate dihydrate particles with a median particle size Dv50 of 100 nm were obtained.
  • Preparation of carbon-coated lithium manganese phosphate Take 1789.6g of the manganese oxalate dihydrate particles obtained above, 369.4g of lithium carbonate (calculated as Li 2 CO 3 , the same below), 1150.1g of ammonium dihydrogen phosphate (calculated as NH 4 H 2 PO 4 , the same below) and 31g sucrose (calculated as C 12 H 22 O 11 , the same below) were added to 20 liters of deionized water, and the mixture was stirred for 10 hours to mix evenly to obtain a slurry. Transfer the slurry to spray drying equipment for spray drying and granulation, set the drying temperature to 250°C, and dry for 4 hours to obtain powder. In a protective atmosphere of nitrogen (90 volume %) + hydrogen (10 volume %), the above powder was sintered at 700° C. for 4 hours to obtain carbon-coated lithium manganese phosphate.
  • Comparative Example 2 Other conditions of Comparative Example 2 were the same as Comparative Example 1 except that 689.5 g of manganese carbonate was used and 463.3 g of additional ferrous carbonate were added.
  • Comparative Example 3 Other conditions of Comparative Example 3 were the same as Comparative Example 1 except that 1148.9 g of ammonium dihydrogen phosphate and 369.0 g of lithium carbonate were used, and 1.6 g of 60% concentration dilute sulfuric acid was additionally added.
  • Comparative Example 4 Except for using 689.5g of manganese carbonate, 1148.9g of ammonium dihydrogen phosphate and 369.0g of lithium carbonate, and additionally adding 463.3g of ferrous carbonate and 1.6g of 60% concentration of dilute sulfuric acid, the other conditions of Comparative Example 4 were the same as those of Comparative Example 4. Same as scale 1.
  • lithium iron phosphate suspension Dissolve 14.7g lithium carbonate, 46.1g ferrous carbonate, 45.8g ammonium dihydrogen phosphate and 50.2g oxalic acid dihydrate in 500ml deionized water, and then stir for 6 hours. The mixture reacted fully. The reacted solution was then heated to 120°C and maintained at this temperature for 6 hours to obtain a suspension containing LiFePO 4 .
  • the sintering temperature in the coating sintering step during the preparation of lithium iron phosphate (LiFePO 4 ) was 600°C.
  • Comparative Example 6 The other conditions of Comparative Example 6 were the same as Comparative Example 4 except that the sintering time was 4h to control the crystallinity of LiFePO 4 to 8%. When preparing carbon-coated materials, the amount of LiFePO 4 was 62.8g.
  • lithium iron pyrophosphate powder Dissolve 2.38g lithium carbonate, 7.5g ferrous carbonate, 7.4g ammonium dihydrogen phosphate and 8.1g oxalic acid dihydrate in 50ml deionized water. The pH of the mixture was 5, and the reaction mixture was stirred for 2 hours to fully react. The reacted solution was then heated to 80°C and maintained at this temperature for 4 hours to obtain a suspension containing Li 2 FeP 2 O 7. The suspension was filtered, washed with deionized water, and dried at 120°C for 4 hours. , get powder. The powder was sintered at 500° C. in a nitrogen atmosphere for 4 hours, and then naturally cooled to room temperature and then ground to control the crystallinity of Li 2 FeP 2 O 7 to 5%.
  • lithium iron phosphate suspension Dissolve 11.1g lithium carbonate, 34.7g ferrous carbonate, 34.4g ammonium dihydrogen phosphate, 37.7g oxalic acid dihydrate and 37.3g sucrose (calculated as C 12 H 22 O 11 , the same below) in 1500 ml deionized water, and then stirred for 6 hours to fully react the mixture. The reacted solution was then heated to 120°C and maintained at this temperature for 6 hours to obtain a suspension containing LiFePO4 .
  • the drying temperature/drying time in the drying step is respectively 80°C/3h, 80°C/3h, and 80°C/ 3h; in the preparation process of lithium iron pyrophosphate (Li 2 FeP 2 O 7 ), the sintering temperature and sintering time in the sintering step are respectively 400°C/3h, 400°C/3h, and 350°C in Comparative Examples 8-10.
  • the drying temperature/drying time in the drying step during the preparation process of lithium iron phosphate (LiFePO 4 ) in Comparative Example 11 is 80°C/3h; and Li 2 FeP 2 O 7 /LiFePO in Comparative Examples 8-11 Except that the dosage of 4 is 47.2g/15.7g, 15.7g/47.2g, 62.8g/0g, and 0g/62.8g respectively, other conditions are the same as those in Examples 1-7.
  • the button battery prepared above was left for 5 minutes in a constant temperature environment of 25°C, discharged at 0.1C to 2.5V, left for 5 minutes, charged at 0.1C to 4.3V, and then charged at a constant voltage of 4.3V until the current was less than Equal to 0.05mA, let stand for 5 minutes; then discharge to 2.5V according to 0.1C.
  • the discharge capacity at this time is the initial gram capacity, recorded as D0, the discharge energy is the initial energy, recorded as E0, and the average discharge voltage V of the buckle is E0 /D0.
  • the above-prepared full cell was stored at 100% state of charge (SOC) at 60°C. Measure the open circuit voltage (OCV) and AC internal resistance (IMP) of the battery cells before, after and during storage to monitor SOC, and measure the volume of the battery cells. The full battery was taken out after every 48 hours of storage, and the open circuit voltage (OCV) and internal resistance (IMP) were tested after leaving it for 1 hour. After cooling to room temperature, the cell volume was measured using the drainage method. The drainage method is to first separately measure the gravity F 1 of the battery cell using a balance that automatically converts units based on the dial data, then completely places the battery core in deionized water (density is known to be 1g/cm 3 ), and measures the battery core at this time.
  • the positive active material sample is prepared into a buckle, and the above buckle is charged at a small rate of 0.05C until the current is reduced to 0.01C. Then take out the positive electrode piece from the battery and soak it in dimethyl carbonate (DMC) for 8 hours. Then it is dried, scraped into powder, and particles with a particle size less than 500nm are screened out. Take a sample and calculate its unit cell volume v1 in the same way as the above-mentioned test of fresh samples, and use (v0-v1)/v0 ⁇ 100% as the lattice change rate (unit cell volume change rate) before and after complete deintercalation of lithium. in the table.
  • DMC dimethyl carbonate
  • the positive electrode active material sample prepared above Take 5 g of the positive electrode active material sample prepared above and prepare a buckle according to the above buckle preparation method. Charge with a small rate of 0.05C until the current is reduced to 0.01C. Then take out the positive electrode piece from the battery and soak it in dimethyl carbonate (DMC) for 8 hours. Then it is dried, scraped into powder, and particles with a particle size less than 500nm are screened out. The obtained particles were measured with electron energy loss spectroscopy (EELS, the instrument model used was Talos F200S) to obtain the energy loss near-edge structure (ELNES), which reflects the state density and energy level distribution of the element. According to the density of states and energy level distribution, the number of occupied electrons is calculated by integrating the valence band density of states data, thereby deducing the valence state of the charged surface oxygen.
  • DMC dimethyl carbonate
  • the crystallinity is the ratio of the crystalline part scattering to the total scattering intensity.
  • the specific embodiments related to the new conductive undercoat layer are added with a suffix [’] after the number.
  • Example 1-1 (positive electrode active material of Example 1-1)
  • the first polymer is a hydrogenated carboxyl nitrile rubber, which contains a first monomer unit, a second monomer unit, a third monomer unit and a fourth monomer unit.
  • the weight percentages of the first monomer unit, the second monomer unit, the third monomer unit and the fourth monomer unit in the polymer, and the weight average molecular weight of the first polymer are as shown in Table 1P.
  • the first monomer unit is the monomer unit represented by Formula 1;
  • the second monomer unit is selected from at least the group consisting of the monomer unit represented by Formula 2 and the monomer unit represented by Formula 3.
  • At least the third monomer unit is selected from the group consisting of the monomer unit represented by Formula 4 and the monomer unit represented by Formula 5.
  • the fourth monomer unit is the monomer unit represented by Formula 6:
  • R 1 , R 2 and R 3 are all H, and R 4 is n-butyl.
  • the first polymer, the first water-based binder (polyacrylic acid-acrylate copolymer, weight average molecular weight 340,000) and the first conductive agent (SP) are mixed in a weight ratio of 15:40:45, and dissolved/dispersed In NMP solvent, prepare conductive primer slurry.
  • the conductive primer slurry is applied to both sides of the aluminum foil, and after drying, a conductive primer with a thickness of 5 ⁇ m is formed on each side.
  • Aluminum foil with a conductive base coating is obtained.
  • the double-layer-coated lithium manganese phosphate cathode active material of Example 1-1 above was mixed with the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) in a weight ratio of 92:2.5:5.5 in N-methyl After mixing evenly in the pyrrolidone solvent system, the positive electrode slurry is obtained. The positive electrode slurry is coated on both sides of the aluminum foil with a conductive undercoat, dried, and cold pressed to form a positive electrode film layer, and a positive electrode piece is obtained. The density of one side of the positive electrode film layer is 0.025g/cm 2 and the compacted density is 2.4g/cm 3 .
  • the density of one side of the negative electrode film layer is 0.013g/cm 2 and the compacted density is 1.7g/cm 3 .
  • PE polyethylene
  • the weight of the positive active material in a single full battery is 565.66g; the weight of the negative active material is 309.38g.
  • Examples 1-2’ to 1-33’ positive electrode active materials of Examples 1-2 to 1-33
  • Example 1-1' The difference between Examples 1-2' to 1-33' and Example 1-1' lies in step 3). Other step parameters are the same as those in Example 1-1'.
  • the cathode active materials used in step 3) of Examples 1-2' to 1-33' are the cathode active materials of the above Examples 1-2 to 1-33 respectively.
  • Examples 2-1’ to 2-3’ positive electrode active materials of Examples 2-1 to 2-3
  • Example 1-1' The difference between Examples 2-1' to 2-3' and Example 1-1' lies in step 3). Other step parameters are the same as those in Example 1-1'.
  • the cathode active materials used in step 3) of Examples 2-1' to 2-3' are the cathode active materials of the above Examples 2-1 to 2-3 respectively.
  • the cathode active materials used in step 3) of Comparative Examples 1' to 7' are the cathode active materials of Comparative Examples 1-1 to 1-7 above, respectively.
  • the cathode active material used in step 3) of Comparative Example 8' is the cathode active material of Example 1-1 above.
  • step 2 The difference between Comparative Example 9' and Example 1-1' lies in step 2).
  • Other step parameters are the same as those in Example 1-1'.
  • step 2 the first water-based binder (polyacrylic acid-acrylate copolymer) and the first conductive agent (SP) were mixed in a weight ratio of 40:45, and dissolved/dispersed in deionized water. water to prepare a conductive primer slurry. The conductive undercoat slurry is applied to the aluminum foil and dried to form a conductive undercoat with a thickness of 5 ⁇ m. Aluminum foil with a conductive base coating is obtained.
  • the first water-based binder polyacrylic acid-acrylate copolymer
  • SP first conductive agent
  • step 2 The difference between Comparative Example 10' and Example 1-1' lies in step 2).
  • Other step parameters are the same as those in Example 1-1'.
  • step 2 the first polymer, the first water-based binder (polyacrylic acid-acrylate copolymer) and the first conductive agent (SP) were mixed in a weight ratio of 15:40:45 , dissolved/dispersed in deionized water, to prepare a conductive primer slurry.
  • the conductive undercoat slurry is applied to the aluminum foil and dried to form a conductive undercoat with a thickness of 5 ⁇ m.
  • Aluminum foil with a conductive base coating is obtained.
  • the difference between the first polymer and the first polymer lies in the composition of the polymer.
  • the composition and weight average molecular weight of the first polymer are as shown in Table 2P below.
  • step 2 The difference between Comparative Example 11' and Example 1-1' lies in step 2).
  • Other step parameters are the same as those in Example 1-1'.
  • step 2 the first polymer, the first binder (polyacrylic acid, weight average molecular weight 350,000) and the first conductive agent (SP) were mixed in a weight ratio of 15:40:45 , dissolved/dispersed in deionized water, to prepare a conductive primer slurry.
  • the conductive undercoat slurry is applied to the aluminum foil and dried to form a conductive undercoat with a thickness of 5 ⁇ m.
  • Aluminum foil with a conductive base coating is obtained.
  • FIG. 2 show a flow chart of the peel test.
  • a steel plate 510 is first provided, with dimensions of 30 mm wide and 100 mm long.
  • a piece of double-sided tape 520 is then provided. The size of the double-sided tape 520 is 20 mm wide ⁇ 30 mm long.
  • the double-sided tape 520 is attached to the steel plate 510, with one wide edge of the double-sided tape 520 Aligned with one wide edge of steel plate 510.
  • a pole piece 530 to be tested is then provided. The size of the pole piece 530 to be tested is 20 mm wide by 180 mm long.
  • the direction of the stretching force is perpendicular to the steel plate 510 and is at a certain distance from the surface of the steel plate 510 .
  • the steel plate moves upward to keep the stretching direction perpendicular to the pole piece peeling position.
  • the stretching causes the pole piece 530 to be gradually peeled off from the steel plate.
  • the stretching speed of the clamp is 50mm/min.
  • record the tensile force of the clamp After the tensile force stabilizes, continue to peel off a length of 40 mm.
  • the average tensile force under the peeling length is the bonding force (unit N).
  • the DC impedance value of the battery of Example 1-1' is 100%, and the changes in other Examples and Comparative Examples relative to Example 1-1' are expressed in the form of percentages.
  • Battery’s 45°C capacity retention rate is 80% cycles (hereinafter referred to as “80% capacity cycles”)
  • the positive electrode sheets of Examples 1-1' to 1-33' and Examples 2-1' to 2-3' show improved adhesion, and the positive electrode sheets of Examples 1-1' to 1-33 ', the batteries of Examples 2-1' to 2-3' showed reduced DC resistance and improved cycle capacity retention rate.
  • Comparative Example 8' (no conductive undercoat layer is provided), Comparative Example 9' (not containing the first polymer), Comparative Example 10' (replacing the first polymer with the first polymer), Comparative Example 11' (using the first polymer) 1 binder instead of the first water-based binder) failed to achieve the above-mentioned improved effect.
  • Example 3-1' to 3-7' lies in step 2).
  • Other step parameters are the same as those in Example 1-1'.
  • step 2) the composition of the first polymer used in Examples 3-1' to 3-7' is different from that in Example 1-1', specifically the weight percentage of the second monomer unit and the third monomer unit. Different from Example 1-1'.
  • the component composition of the first polymer of Examples 3-1' to 3-7' is shown in Table 4P below.
  • Example 3-8' to 3-12' lies in step 2).
  • Other step parameters are the same as those in Example 1-1'.
  • step 2) the thickness of the conductive undercoat layer of Examples 3-8' to 3-12' is different from that of Example 1-1', see Table 5P for details.
  • Example 1-1' The difference between Examples 3-13' to 3-18' and Example 1-1' lies in step 2).
  • Other step parameters are the same as those in Example 1-1'.
  • step 2) the conductive undercoat components (the ratio of the first polymer, the first aqueous binder and the first conductive agent) of Examples 3-13' to 3-18' are the same as those of Example 1-1 'Different, see Table 6P for details.
  • the adhesion force of the positive electrode sheet prepared in the above embodiments 1-1', 3-1' to 3-18', the DC resistance value of the battery and the 45°C capacity retention rate of the battery were 80 % cycle number was tested, and the results are shown in Table 7P below.
  • Example 3-1 13 100% 1650
  • Example 3-1 12.7 100% 1700
  • Example 3-2’ 13 97% 1688
  • Example 3-3 12.5 100% 1703
  • Example 3-4 13.1 99% 1600
  • Example 3-5 13.8 98% 1660
  • Example 3-6 13.9 99% 1655
  • Example 3-7 12 258% 731
  • Example 3-8 8.5 110% 1540
  • Example 3-9 7.3 101% 1720
  • Example 3-10 9.9 100% 1779
  • Example 3-11’ 21.1 120% 1600
  • Example 3-13’ 8.1 100% 1630
  • Example 3-14’ 10.5 105% 1680
  • Example 3-15’ 11.6 103% 1701
  • Example 3-16’ 10.7 145% 1600
  • Example 3-17’ 14.5 130% 1635
  • Example 3-18’ 15 110% 1630
  • Example 4-1' to 4-9' lies in step 3).
  • Other step parameters are the same as those in Example 1-1'.
  • step 3) of Examples 4-1' to 4-9' the double-layer coated lithium manganese phosphate cathode active material of Example 1-1 above is mixed with the conductive agent acetylene black and the binder polyylidene fluoride.
  • Ethylene (PVDF), dispersant and sizing agent are mixed evenly in the N-methylpyrrolidone solvent system according to the weight ratio (92-Y 1 -Y 2 ): 2.5: 5.5: Y 1 : Y 2 to obtain the positive electrode slurry.
  • the positive electrode slurry is coated on both sides of the aluminum foil with a conductive undercoat, dried and cold pressed to form a positive electrode film layer to obtain a positive electrode piece.
  • the density of one side of the positive electrode film layer is 0.025g/cm 2 and the compacted density is 2.4g/cm 3 .
  • the sizing agent in Examples 4-1' to 4-9' is maleic anhydride-styrene copolymer (molecular weight 5000).
  • the dispersant of Examples 4-1' to 4-9' is the second polymer.
  • the second polymer is a hydrogenated nitrile rubber containing a fifth monomer unit, a sixth monomer unit and a seventh monomer unit.
  • the weight percentages of the five monomer units, the sixth monomer unit and the seventh monomer unit in the polymer, and the weight average molecular weight of the second polymer are shown in Table 8P.
  • the fifth monomer unit is the monomer unit represented by Formula 1;
  • the sixth monomer unit is at least one selected from the group consisting of the monomer unit represented by Formula 8 and the monomer unit represented by Formula 9.
  • the seventh monomer unit is at least one selected from the group consisting of the monomer unit represented by Formula 10 and the monomer unit represented by Formula 11;
  • the mass ratio of the first polymer (from the conductive undercoat layer) and the second polymer (from the positive electrode film layer) is 2:1.
  • the ratio Y 1/ Y 2 is shown in Table 9P below.
  • Example 4-1 0.2 0.3 0.67
  • Example 4-2 0.1 0.5 0.20
  • Example 4-3 0.5 0.5 1.00
  • Example 4-4 1 0.5 2.00
  • Example 4-5 0.25 0.05 5.00
  • Example 4-6 0.25 0.2 1.25
  • Example 4-7 0.25 0.3 0.83
  • Example 4-8 0.25 0.8 0.31
  • Example 4-9 0.25 2 0.13
  • Example 1-1 13 100% 1650
  • Example 4-1 64 93% 1762
  • Example 4-2 60 95% 1770
  • Example 4-3 178 104% 1310
  • Example 4-4 193 160% 1308
  • Example 4-5 105 100% 1700
  • Example 4-6 105 99% 1830
  • Example 4-7 110 98% 1781
  • Example 4-8’ 108 106% 1690
  • Example 4-9’ 109 116% 1410
  • the adhesion of the electrode piece can be further improved, and/or the DC resistance of the battery can be reduced, and /or improve battery cycle performance.
  • the positive electrode plate includes a new positive active material and a new conductive undercoat.
  • New cathode active materials have achieved better results in one or even all aspects of cycle performance, high-temperature storage performance and safety performance.
  • the new conductive undercoating achieves better results in one or even all aspects of providing adhesion to the pole pieces, reducing the DC resistance of the battery, and improving the cycle performance of the battery.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

La présente demande concerne une feuille d'électrode positive, une batterie secondaire et un appareil électrique. La feuille d'électrode positive comprend un collecteur de courant d'électrode positive, une couche de film d'électrode positive disposée sur au moins une surface du collecteur de courant d'électrode positive et un revêtement inférieur conducteur situé entre le collecteur de courant d'électrode positive et la couche de film d'électrode positive, la couche de film d'électrode positive comprenant un matériau actif d'électrode positive ayant une structure noyau-enveloppe, le matériau actif d'électrode positive comprenant un noyau interne et une enveloppe recouvrant le noyau interne, et le revêtement inférieur conducteur comprenant un premier polymère, un premier liant à base d'eau et un premier agent conducteur.
PCT/CN2022/084385 2022-03-31 2022-03-31 Feuille d'électrode positive, batterie secondaire et appareil électrique WO2023184329A1 (fr)

Priority Applications (4)

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CN202280050821.9A CN117678092A (zh) 2022-03-31 2022-03-31 正极极片、二次电池及用电装置
EP22917641.7A EP4280308A4 (fr) 2022-03-31 2022-03-31 Feuille d'électrode positive, batterie secondaire et appareil électrique
PCT/CN2022/084385 WO2023184329A1 (fr) 2022-03-31 2022-03-31 Feuille d'électrode positive, batterie secondaire et appareil électrique
US18/222,503 US20230420677A1 (en) 2022-03-31 2023-07-17 Positive electrode plate, secondary battery and power consuming device

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CN103069624A (zh) * 2010-07-01 2013-04-24 夏普株式会社 正极活性材料、正极和非水二次电池
JP2014056722A (ja) * 2012-09-13 2014-03-27 Asahi Glass Co Ltd リン酸化合物、二次電池用正極材料、および二次電池の製造方法
CN106058225A (zh) * 2016-08-19 2016-10-26 中航锂电（洛阳）有限公司 核壳结构LiMn1‑xFexPO4正极材料及其制备方法、锂离子电池
CN106816600A (zh) * 2015-11-30 2017-06-09 比亚迪股份有限公司 一种磷酸锰铁锂类材料及其制备方法以及电池浆料和正极与锂电池
CN109301174A (zh) * 2017-07-24 2019-02-01 宁德时代新能源科技股份有限公司 正极材料及其制备方法及锂二次电池
CN110431697A (zh) * 2017-03-22 2019-11-08 株式会社Lg化学 制备二次电池正极用浆料组合物的方法、利用该方法制备的二次电池用正极、和包含该正极的锂二次电池
CN114174384A (zh) * 2020-01-07 2022-03-11 株式会社Lg化学 预分散剂组合物、和包括所述预分散剂组合物的电极和二次电池

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JPH1173943A (ja) * 1997-08-29 1999-03-16 Toshiba Corp 非水系電解液二次電池
CN103069624A (zh) * 2010-07-01 2013-04-24 夏普株式会社 正极活性材料、正极和非水二次电池
JP2014056722A (ja) * 2012-09-13 2014-03-27 Asahi Glass Co Ltd リン酸化合物、二次電池用正極材料、および二次電池の製造方法
CN106816600A (zh) * 2015-11-30 2017-06-09 比亚迪股份有限公司 一种磷酸锰铁锂类材料及其制备方法以及电池浆料和正极与锂电池
CN106058225A (zh) * 2016-08-19 2016-10-26 中航锂电（洛阳）有限公司 核壳结构LiMn1‑xFexPO4正极材料及其制备方法、锂离子电池
CN110431697A (zh) * 2017-03-22 2019-11-08 株式会社Lg化学 制备二次电池正极用浆料组合物的方法、利用该方法制备的二次电池用正极、和包含该正极的锂二次电池
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US20230420677A1 (en) 2023-12-28

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